Centaurea diffusa
Diffuse knapweed
Family: Asteraceae · Type: perennial · Not Native
Conservation status: Cal-IPC Yes
Diffuse knapweed is a naturalized perennial herb found in northwestern California, the Cascade Range, northern and central Sierra Nevada, Sacramento Valley, San Francisco Bay Area, southern Coast Ranges, San Bernardino Mountains, and Modoc Plateau in fields, roadsides, and open woodlands at elevations below 2,300 meters. Flowering from May to October, this plant produces creamy white to lavender flowers in heads 10 to 13 millimeters long, arranged in open panicle-like clusters. Growing with much-branched stems 20 to 80 centimeters tall that are puberulent and grayish-tomentose, it develops a complex branching structure. Its leaves are distinctively divided, with basal and lower stem leaves 10 to 20 centimeters long, deeply 2-pinnately divided into linear to oblong lobes, while upper stem leaves become progressively less divided. The plant's distinctive involucre features pale green phyllaries with prominent parallel veins and fringed appendages ending in straw-colored spines 1 to 3 millimeters long.
Habitat: Fields, roadsides, open woodland
Bloom period: May-Oct
Elevation: < 2300 m
Bioregions: NW, CaR, n&c SN, ScV, SnFrB, SCoR, SnBr, MP, W&I
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.